638916768 has 192 divisors, whose sum is σ = 2147040000. Its totient is φ = 181066752.

The previous prime is 638916767. The next prime is 638916779. The reversal of 638916768 is 867619836.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (638916767) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 900798 + ... + 901506.

It is an arithmetic number, because the mean of its divisors is an integer number (11182500).

Almost surely, 2^638916768 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638916768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1073520000).

638916768 is an abundant number, since it is smaller than the sum of its proper divisors (1508123232).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638916768 is a wasteful number, since it uses less digits than its factorization.

638916768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 884 (or 870 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 54.

The square root of 638916768 is about 25276.8029624001. The cubic root of 638916768 is about 861.2874029915.

The spelling of 638916768 in words is "six hundred thirty-eight million, nine hundred sixteen thousand, seven hundred sixty-eight".